In a scientific field where a chain-type biopolymer such as a nucleic acid molecule like DNA is measured by a single molecule using a high space-resolution microscope such as a scanning tunneling microscope, it is necessary to immobilize the chain-like biopolymer on a substrate in an elongated state, and a method of preparing a sample for such measurement is known.
In one example of conventional sample preparing methods, after immobilizing a nucleic acid molecule by adding a nucleic acid molecule solution dropwise onto a substrate of highly-oriented graphite or the like, the solution remaining on the substrate is blown off by centrifugal force or by air, whereby the nucleic acid molecule is elongated.
In other examples of methods, a nucleic acid molecule is elongated by a shearing force generated by liquid flow after immobilization of the nucleic acid molecule on a substrate; or a nucleic acid molecule is elongated on a substrate by utilizing surface tension of a gas-liquid interface that is retreating from the site where the nucleic acid molecule is immobilized (see Patent document 1, and Non-patent document 1).
Patent document 1: Japanese Unexamined Patent Publication No. 2005-49176.
Non-patent document 1: D. C. G. Klein, L. Gurevich, J. W. Janssen, L. P. Kouwenhoven, J. D. Carbeck, and L. L. Sohn, “Ordered stretching of single molecules of deoxyribose nucleic acid between microfabricated polystyrene lines,” Appplied Physics letters, Volume 78, Number 16, 2001, pp. 2396-2398.